MouseOver & Coordinates

[Stefan Schwarzer]

Thanks Martin for that. The only thing I am not sure about is how the  
javascript variable, which holds the information about the pixel size,  
should be called. How does this variable get into the Javascript  
functions?

Thanks for your help - and congratulations to your planiglobe.com site.  
Looks really neat!!

Stef


> On Thursday 10 March 2005 11:07, Stefan Schwarzer wrote:
>> Hi,
>>
>> I would like to display the coordinates in a corner of the map, when a
>> user moves the mouse over it. Is there any Javascript (or Java) code
>> out there that would do this?
>>
>> Thanks for any suggestions.
>>
>> Stef
>
> Stefan,
>
> you need to know the pixel size of your map image in map units (DD,  
> meters,..).
> using MapScript you can pass this value along with every new map  
> generated
> as a (hidden) value and set a javascript object or variable to this  
> value.
> With mapserver CGI you must calculate this value by image size and map  
> extent
> yourself.
>
> Next you define an eventhandler for the mouseover event of your map  
> image,
> for instance:
>
> function MapElmOverHndl(e) {
>   var imgOrig = theMap.getorig();
>   var posx = ((e.offsetX * theMap.getcsz())+imgOrig[0]);
>   var posy = (((400-e.offsetY) * theMap.getcsz())+imgOrig[1]));
>   Dspl.innerHTML=posx+' '+posy;
> }
>
> 'theMap.getorig()':  returns minx, miny (mapunits) of the current image
> 'theMap.getcsz()': returns the cellsize (pixelsize) in mapunits
> '400' is the image height in pixels
> 'Dspl' is a document element like <p>, <td>, <div> or some such.
>
> Once you got the handler you add this event handler to your map image.
> If your map image got an id of - say - 'myMap':
>
> for DOM-Browsers you type:
> document.getElementById('myMap').addEventListener("mousemove",MapElmOve 
> rHndl , false)
>
> for IE6 you type:
> document.all['myMap''].attachEvent("onmousemover", MapElmOverHndl);
>
> A cross browser solution could look similar to:
> var d= document;
> if (!d.getElementById && d.all) d.getElementById = new Function('id',  
> 'return d.all[id]');
>
> function X_addEventListener(elm, evt, lstnr, useCapture) {
>   (! elm.addEventListener && d.all)? elm.attachEvent('on'+evt, lstnr)  
> : elm.addEventListener(evt, lstnr, useCapture);
> }
>
> Now you add the listener by:
> myMapElm= d.getElementById('myMap');
> X_addEventListener(myMapElm ,"mousemove", MapElmOverHndl, false);
>
> Cheers, Martin
>
>

        _______________________________________

        Stefan Schwarzer
        GIS & Data Management

        UNEP/DEWA/GRID-Geneva
        Chemin des Anemones 11
        CH - 1219 Chatelaine
        Switzerland

        Tel: (+41) 22.917.83.49
        Fax: (+41) 22.917.80.29

        Internet: http://geodata.grid.unep.ch/
        _______________________________________
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